package com.demo.jdksource;

import java.io.IOException;
import java.util.concurrent.ConcurrentHashMap;

public class TestCurrentHashmap {
    public static void main(String[] args) throws IOException {
        ConcurrentHashMap concurrentHashMap = new ConcurrentHashMap();
        concurrentHashMap.put("a","123");
        concurrentHashMap.put(null,null);
    }
}
